Molecular characterization of bacterial pathogens of fresh water fishes
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Date
2006
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Publisher
CCSHAU
Abstract
The present investigation was carried out to identify the
fish pathogens causing diseases in (catla, rohu, mrigal, grass
carp, puthi, murrels and Thai magur). A number of biochemical
tests were carried out for identification of bacterial fish
pathogens. The bacterial diseases were identified viz. EUS, fin
and tail rot, gill rot and haemorrhagic septicemia in village
ponds/ fish farms (Charanjeet fish farm, Hansi, Siswala village
pond, Satrod village pond, Ishwar Singh fish farm, Dabra, Rajli
village pond, Kirtan village pond) from July, 2005 to March,
2006. Diseases were observed in July, September, November,
2005 and January, 2006. No disease was found in August,
October, December, 2005 and January, 2006. Two gram positive
cocci (Staphylococcus aureus, Streptococcus grp.Q1) and seven
gram negative rods (Aeromonas hydrophila, Enterobacter
aerogenes, E. cloacae, Klebsiella oxytoca, Citrobacter koseri,
Pseudomonas aeruginosa, P. fluorescens) bacterial pathogens
were isolated and identified from affected fishes. Amplification of
genomic DNA of seven isolates (S. aureus, Kl. Oxytoca, E. cloacae,
A. hydrophila, P. fluroescens, P. aeruginosa, Streptococcus grp Q
1) was carried out and ARDRA profiles were prepared by using
Hinf1 and SauIIIA restriction endonucleases, separately.
Phylogenetic similarity of all seven isolates was analyzed by
NTSYSpc 2.0 programme. On the basis of similarity coefficient
the isolates were divided in five major groups (A, B, C, D, and E).
Group A is most diverse, which had genotype S. aureus followed
by group E and group C contained genotypes Streptococcus grp.
Q1 and E. cloacae, respectively. The genotypes Kl. oxytoca and A.
hydrophila had 83% similarity, in-group B whereas P. fluorescens
and P. aeruginosa had 99% similarity in-group D.